Hepatic regeneration is important for the recovery and ultimate prognosis of patients with alcoholic liver disease. In vivo and in vitro studies have implicated specific growth factors, i.e., epidermal growth factor, insulin and glucagon, as necessary for liver regeneration. In some studies, ethanol inhibited both DNA synthesis, as measured by [3H]-thymidine incorporation, and hepatocyte proliferation. To extend these studies in a model which permits control of many variables, three human-derived cell lines, which have the morphologic and functional characteristics of hepatocytes, will be used to evaluate the effects of ethanol on growth regulation of hepathocytes. These cell lines comprise the hepathoblastoma-derived HepG2, and Hep3B and PLC/PRF/5, derived from human hepatocellular carcinomas. The studies will also be extended to a mouse liver-derived cell line originating from bile duct epithelium. Initial studies will explore conditions essential for the induction of DNA synthesis, cell proliferation and long-term maintenance of cultures in serum-free, chemically-defined medium. Specific growth factors and receptor dynamics will be examined throughout the growth cycle both quantitiatively, by I125-ligand binding studies and radio-immunoassays, and functionally, by measurement of receptor protein kinase activity and by biosynthetic labelling. These experiments will be performed with the addition of varying concentrations of ethanol, both acutely and chronically. Using pyrazole to inhibit ethanol metabolism, changes will be ascribed to the presence of ethanol or to its metabolism, or both. A clearer understanding of growth regulation in hepatocytes may eventually have therapeuctic implications.